JSFiddle - React, Tailwind, and code Playground

HTML

<div class="outer">
    <img src="http://placekitten.com/g/200/300" />                    
        <div class="overlay">
            <p class="text">x</p>
        </div>
    </div>

CSS

.outer {
    position:relative;
    width: 200px;
    height: 300px;
}
.overlay {						
    display: block;
    position: absolute;
    width: 100%;
    height: 100%;
    background: black;
    opacity: 0.7;
    top: 0;
}

.outer:hover .overlay {	
    display: block;
    position: absolute;
    width: 100%;
    height: 100%;
    background: black;
    opacity: 0.7;
    top: 0;
}
.text {
    position: absolute;
    top: 50%;
    left: 50%;
    transform:translate(-50%, -50%);
    color:white;
}